Insituform Technologies, Inc. v. Cat Contracting, Inc.

Harold James, Epstein Drangel Bazerman & James LLP, of New York, NY, for plaintiffs-cross appellants.

Arnold Anderson Vickery, of Houston, TX, for CAT Contracting, Inc., et al.

N. Elton Dry, Dry & Tassin, LLP, of Houston, TX, for defendant-appellant Michigan Sewer Construction Company.

Richard L. Stanley, Howrey Simon Arnold & White, LLP, of Houston, TX, for defendant-appellee Kanal Sanierung Hans Mueller GmbH & Co., KG. With him on the brief was Albert B. Deaver, Jr.

Before MAYER, Chief Judge, MICHEL, and SCHALL, Circuit Judges.

SCHALL, Circuit Judge.

Defendants Cat Contracting, Inc. ("CAT"), Firstliner U.S.A., Inc. ("Firstliner"), Giulio Catallo (sometimes referred to as "Catallo"), and Michigan Sewer Construction Company ("MSC") ("defendants") appeal the judgment of the United States District Court for the Southern District of Texas holding them liable for infringement of United States Patent No. 4,366,012 ("the' 012 patent") and awarding plaintiffs Insituform Technologies, Inc. ("Insituform Technologies"), Insituform (Netherlands) B.V. ("Insituform Netherlands"), and Insituform Gulf South, Inc. ("Insituform Gulf") ("plaintiffs") damages for that infringement. Insituform Techs., Inc. v. Cat Contracting, Inc., No. H-90-1690, slip op. (S.D.Tex. Aug. 31, 1999) ("District Court Opinion"). Defendants also appeal the joinder of Insituform Netherlands as a plaintiff. Id. at 21-22. In addition, CAT, Firstliner, and Catallo appeal the district court's joinder of Catallo as a defendant. Insituform Techs., Inc. v. Cat Contracting, Inc., No. H-90-1690, slip op. at 9 (Aug. 30, 1999) ("Joinder Order"). For their part, plaintiffs cross-appeal the ruling of the district court declining to hold defendant Kanal Sanierung Hans Mueller GmbH & Co. KG ("KS") vicariously liable to plaintiffs under an alter-ego theory of induced infringement. District Court Opinion, slip op. at 44-45.

We affirm the judgment of infringement with respect to all defendants. We also affirm the district court's joinder of Insituform Netherlands as a plaintiff, its joinder of Giulio Catallo as a defendant, and its ruling declining to hold KS vicariously liable for induced infringement. However, we vacate the judgment that the infringement of CAT and Firstliner was willful and remand for further proceedings on the issue of willful infringement. We also vacate the district court's damages award and remand for further proceedings to determine damages based on when defendants ceased selling the pipe repair process that was found to infringe the '012 patent. Accordingly, we affirm-in-part, vacate-in-part, and remand.

Underground pipes, such as sewer pipes, are often subject to great stress. As a result, over time, the pipes develop cracks and other structural defects, which can result in leakage. In the past, the only way to rehabilitate a section of underground pipe was to dig up the broken section and replace it. Eric Wood, the sole inventor named on the '012 patent, pioneered a process for rehabilitating underground pipe without digging it up.

The '012 patent discloses Wood's invention. The patent relates to a method for performing pipe repair without removing the damaged pipe from the ground. The method involves installing a liner into the pipe. Claim 1 of the patent, the only claim at issue, claims a process for impregnating a flexible tube liner with resin prior to insertion of the liner into a damaged pipe. The liner has an impermeable film on the outside and a resin-absorbent, felt layer on the inside. A vacuum is applied to the inside of the liner by cutting a window into the outer, impermeable film, applying a cup (a "vacuum cup") to the outside of the window, and connecting the other end of the cup to a vacuum source. Using the created vacuum, a section of the inside of the liner is impregnated with resin, which is drawn through the liner. The vacuum cup is then moved to another section of the liner while the previously used window is sealed. This process for impregnating the liner with resin allows for impregnation at the jobsite, eliminating the need to transport a heavier, already impregnated liner to the site.

This case has a lengthy procedural history. The issues before us arise from a complex series of trials, appeals, and cross-appeals that now span nearly fourteen years. We briefly review each significant decision in turn.

The original defendants in this action were CAT, Inliner U.S.A., Inc. ("Inliner"), MSC, and KS. Inliner subsequently changed its name to Firstliner U.S.A., Inc., and we refer to this defendant as Firstliner throughout. Firstliner and CAT are in the business of rehabilitating and restructuring various types of pipes, including sanitary, storm sewer, water main, conduit, and industrial pipe. District Court Opinion, slip op. at 5. Firstliner oversees the marketing of its trenchless procedure for pipe rehabilitation to potential licensees. Id. In addition, Firstliner manufactures pipeliners and related materials, which it sells to CAT and its licensees. Id. CAT is responsible for marketing, bidding for, and negotiating contracts with customers and managing its pipeline rehabilitation contracts. Id. Giulio Catallo, who was subsequently added as a defendant, is the individual principal of both CAT and Firstliner. MSC is also in the pipe rehabilitation business. CAT was involved in a joint venture with MSC for performing the accused processes.

KS is a German sewer rehabilitation company owned by Hans Mueller. After reading about KS's proprietary sewer rehabilitation technology in a trade magazine, Giulio Catallo contacted KS to obtain a license for that technology. Id. Catallo subsequently acquired the rights to use the accused processes from Kanal Mueller Gruppe International GmbH & Co. ("Gruppe"), a German export licensing company also owned by Hans Mueller. Although KS stated in a letter written on November 10, 1989, that CAT was a "qualified Licensee for our KM-INLINER sewer relining process for the territories of the USA," there was no formal license agreement executed by the parties. Id. at 6. An actual license agreement, however, was later executed between Gruppe and Firstliner, permitting CAT's use of the accused process. Id. This license agreement stated that "[t]he licensee has been informed of a threat of a possible claim for infringing the INSITUFORM method." Id.

The original accused process used by defendants — referred to as the "Multiple Cup Process" or "Process 1" — was a method of tube liner impregnation involving the serial application of vacuum cups. In Process 1, from four to six cups were used to draw a vacuum from a corresponding number of slits in the tube liner. As a result, when the cup closest to the advancing resin was removed, and its slit was sealed, the remaining downstream cups continued to draw a vacuum in the tube liner.

At some point in either 1991 or early 1992, on the advice of counsel, defendants switched to an alternate process. In the alternate process — referred to as the "Multiple Needle Process" or "Process 2" — the multiple cups were replaced with multiple metal tubes, known as needles. In Process 2, the needles are inserted through the layers of the impregnated tube liner, rather than merely placed over holes in the wall of the liner. Defendants did not develop Process 2 until after the first phase of the case had already been tried to a jury.

The original action for infringement of the '012 patent was brought in February 1990. The original plaintiffs were Insituform of North America, Inc.; Insituform Licensees, B.V.; and Insituform Gulf. Insituform Licensees, B.V. was the owner of the '012 patent at the commencement of the suit. As explained more fully below, Insituform Licensees, B.V. subsequently assigned the '012 patent to Insituform Netherlands, along with the right to sue for past infringement. Insituform Netherlands was thus eventually substituted for Insituform Licensees, B.V. as a plaintiff. Insituform Technologies, Inc. ("ITI") is the parent company and administrative headquarters for the Insituform organization, including Insituform Gulf. Id. at 4. Insituform Gulf is authorized to do business in Louisiana, Mississippi, and Texas and licensed to perform Insituform technology in designated regions throughout the United States.1 Id. at 5. Insituform of North America, Inc. is no longer a party to the suit.

Only claim 1 of the '012 patent was asserted at trial. It recites

1. A method of impregnating with a curable resin an inner layer of resin absorbent material disposed in an elongate flexible tube having an outer layer formed by an impermeable film, the method comprising the steps of

(1) introducing into one end of the elongate tube a mass of the curable resin sufficient to impregnate the entire resin absorbent inner layer of the tube,

(2) forming a window in the impermeable outer layer of the tube at a distance from said one end of the tube,

(3) drawing through the window a vacuum in the interior of the tube downstream of said one end by disposing over the window a cup connected by a flexible hose to a vacuum source which cup prevents ingress of air into the interior of the tube while the tube is being evacuated, the outer layer of the tube being substantially impermeable to air,

(4) beginning at or near the end at which the curable resin mass was introduced, passing the tube between squeezing members which force the resin to flow towards the region of vacuum application as the tube progresses through the squeezing members,

(5) when the resin reaches the vicinity of the region of vacuum application, removing the cup and sealing the window,

(6) providing another window in the impermeable layer of the tube downstream of the previously formed window,

(7) drawing through the new window a vacuum in the interior of the tube while progressively moving the tube through the squeezing members to force the resin to flow toward the new region of vacuum application, and

(8) repeating steps 5, 6, and 7, where necessary to impregnate the entire resin absorbent inner layer of the flexible tube.

'012 patent, col. 6, l. 37 — col. 7, l. 6.

The case was first tried to a jury in June 1991. The jury returned a verdict that the '012 patent was not invalid and was infringed, both literally and via equivalents, by Process 1, the only accused process then at issue. The district court granted defendants' motion for judgment notwithstanding the verdict ("JNOV") with respect to literal infringement and ordered a new trial as to infringement under the doctrine of equivalents. In June 1994, the case was reassigned to a different judge. A bench trial was held in February 1995, and in November of that year the court held that Process 1 and Process 2 (which had been introduced after the 1991 trial) infringed the '012 patent under the doctrine of equivalents. The court held defendants CAT, Firstliner, and MSC liable for direct infringement. The court also found CAT and Firstliner liable for induced infringement. Additionally, the court found that KS also had induced infringement of the '012 patent. Defendants appealed.

On appeal, we ruled that claim 1 of the '012 patent, which recites use of a ngle cup moved to different windows along the tube to draw a vacuum, did not encompass the accused methods of using several cups or several needles attached at different points along the tube, and thus was not literally infringed by either Process 1 or Process 2. Insituform Techs., Inc. v. Cat Contracting, Inc., 99 F.3d 1098, 1106-07 (Fed.Cir.1996) ("Insituform I"). We also ruled that plaintiffs were not barred by prosecution history estoppel from asserting infringement under the doctrine of equivalents. Id. at 1107-08. Finally, we ruled that the district court had erred in construing claim 1. We therefore vacated the judgment of infringement with respect to both processes under the doctrine of equivalents and remanded the case for new findings regarding infringement under the doctrine of equivalents under the correct claim construction. Id. Because we vacated the judgment of direct infringement, we did not reach the issue of whether KS had induced infringement of the '012 patent.

On remand, the district court again held that claim 1 of the '012 patent was infringed by both Process 1 and Process 2 under the doctrine of equivalents. Insituform Techs., Inc. v. Cat Contracting, Inc., 99 F.3d 1098 (S.D.Tex.1996). The court subsequently enjoined defendants from practicing those processes. In addition, the court ruled again that KS had induced infringement of the '012 patent. Defendants again appealed.

On the second appeal to us, we reaffirmed that prosecution history estoppel did not bar plaintiffs from asserting infringement under the doctrine of equivalents. Insituform Techs., Inc. v. Cat Contracting, Inc., 161 F.3d 688, 692 (Fed.Cir.1998) ("Insituform II"). On the infringement issue, insofar as Process 1 was concerned, we affirmed the district court's holding that the process infringed claim 1 of the '012 patent under the doctrine of equivalents. Id. at 693. However, with respect to Process 2, we held that there were substantial differences between the claimed single cup process and the accused multiple needle process. Id. at 694. Accordingly, we reversed the court's holding that Process 2 infringed. Id.

Turning to the liability of KS2 for induced infringement, we noted that "a separate corporation related to [KS] licensed the infringing technology to [Firstliner] after [KS] received notice of the '012 patent." Id. at 695. That corporation was Gruppe. Because Gruppe was not a party to the case, and because "there were no findings that this affiliate was [KS]'s alter ego," we vacated the district court's holding and remanded for further proceedings on the inducement issue. Id. D. Insituform III

On remand, the district court determined that Gruppe was not the alter ego of KS and that KS, therefore, was not liable for induced infringement. District Court Opinion, slip op. at 45. Additionally, the district court joined Giulio Catallo in his personal capacity as a defendant, and held him jointly liable for damages. Joinder Order, slip op. at 9. With both the liability and damages trials now concluded, the court awarded damages for infringement of the '012 patent by Process 1 under the doctrine of equivalents. District Court Opinion, slip op. at 62. Additionally, the court found CAT and Firstliner's infringement to be willful and thus enhanced the actual damages award by fifty percent, id. at 55, and awarded Insituform attorney fees, id. at 57.

Defendants appealed, raising a number of different issues. These included (1) whether Insituform Netherlands, the new assignee of the '012 patent, had been improperly joined as a plaintiff; (2) whether Giulio Catallo, as president of CAT, had been improperly joined as an individual defendant jointly and severally liable for damages; (3) whether the district court had properly assessed damages following our decision in Insituform II; (4) whether the district court had erred in holding that the infringement that was found in the case was willful; and (5) whether the district court had erred in determining the extent to which accused infringers CAT and Firstliner instructed, and therefore induced, their licensees to use the infringing process. For their part, plaintiffs cross-appealed the district court's ruling that Gruppe was not the alter ego of KS and that KS therefore was not vicariously liable for induced infringement.

After oral argument in the appeal, defendants filed motions asking us to apply our holding in Festo Corp. v. Shoketsu Kinzoku Kogyo Kabushiki Co., Ltd., 234 F.3d 558 (Fed.Cir.2000) (en banc) ("Festo I"). In Festo I, we ruled that a narrowing amendment to a claim limitation made for a substantial reason related to patentability completely bars the application of the doctrine of equivalents to that amended claim limitation. Id. at 569. Because our Festo I decision represented an intervening change in controlling authority, we revisited our infringement holdings in Insituform I and II. Insituform Techs., Inc. v. CAT Contracting, Inc., 10 Fed.Appx. 871, 877 (Fed.Cir.2001) (unpublished) ("Insituform III").

After reexamining the prosecution history of the '012 patent, we determined that, under Festo I, Insituform had made a narrowing amendment to claim 1 of the '012 patent. Insituform III, 10 Fed.Appx. at 879-80. The claim was narrowed, we pointed out, because claim 1 in its original form did not limit the number of cups that could be used to create a vacuum, whereas claim 1 in its amended form was limited to the use of one cup. Id. Accordingly, we held that "Insituform cannot assert any range of equivalents for this claim limitation [and] Process 1, which uses multiple cups, cannot infringe under the doctrine of equivalents, the only finding of infringement affirmed by this court." Id. at 880. We therefore reversed the district court's final judgment of liability and damages, and remanded the case with instructions "(i) to vacate all orders entered after the finding of infringement as moot, including those relating to damages and Catallo's joinder as defendant; and (ii) to dismiss the case as to all parties." Id. We thus did not address the several remaining issues noted above that originally were on appeal to us in Insituform III. Plaintiffs petitioned the Supreme Court for a writ of certiorari, as did the plaintiff in Festo I.

The Supreme Court vacated and remanded our decision in Festo I. Festo Corp. v. Shoketsu Kinzoku Kogyo Kabushiki Co., Ltd., 535 U.S. 722, 122 S.Ct. 1831, 152 L.Ed.2d 944 (2002) ("Festo II"). In Festo II, the Court overruled the complete bar we established in Festo I, establishing a flexible bar instead. Id. at 738, 122 S.Ct. 1831 ("[W]e have consistently applied the doctrine [of equivalents] in a flexible way, not a rigid one."). The Court also held, inter alia, that where the equivalent was "unforeseeable at the time of the amendment" or the rationale underlying the amendment bore "only a peripheral relation" to the equivalent, the patentee could rebut the so-called "Festo-presumption." Id. at 740, 122 S.Ct. 1831. That presumption is that a narrowing amendment made for a reason of patentability surrenders the entire territory between the original and the amended claim limitation. Id. Accordingly, the Court vacated our decision in Insituform III and remanded the case to us for further proceedings in light of its decision in Festo II. Insituform Techs., Inc. v. CAT Contracting, Inc., 535 U.S. 1108, 122 S.Ct. 2322, 153 L.Ed.2d 151 (2002).

After the Supreme Court remanded Festo to us, we rendered our second en banc decision in the case. Festo Corp. v. Shoketsu Kinzoku Kogyo Kabushiki Co., Ltd., 344 F.3d 1359 (Fed.Cir.2003) ("Festo III"). In Festo III, we summarized the three ways in which the Supreme Court stated that the Festo presumption could be rebutted. Id. at 1369. First, the patentee may demonstrate that "the alleged equivalent would have been unforeseeable at the time of the narrowing amendment." Id. Second, the patentee may demonstrate that "the rationale underlying the narrowing amendment bore no more than a tangential relation to the equivalent in question." Id. Finally, there may be "`some other reason' suggesting that the patentee could not reasonably have been expected to have described the alleged equivalent." Id. (citing Festo II, 535 U.S. at 740-41, 122 S.Ct. 1831).

The following issues are now before us on direct appeal: (1) whether plaintiffs are barred from asserting infringement under the doctrine of equivalents by reason of prosecution history estoppel in light of Festo II and Festo III; (2) whether Insituform Netherlands, the new assignee of the '012 patent, was improperly joined as a plaintiff; (3) whether Giulio Catallo, president of CAT, was improperly joined as an individual defendant and held jointly and severally liable for damages; (4) whether the district court properly assessed damages following our decision in Insituform II; (5) whether the district court erred in holding that the infringement that was found in this case was willful; and (6) whether the district court erred in determining the extent to which accused infringers CAT and Firstliner instructed their licensees to use the infringing process. On cross-appeal, we consider whether the district court erred in ruling that Gruppe was not the alter ego of KS, and that KS therefore was not vicariously liable for induced infringement. We address the parties' contentions in turn, beginning with the Festo issue.

With the complete bar of Festo I overturned, we asked the parties to give us their views as to how we should decide the case in light of Festo II and Festo III. In response, both plaintiffs and defendants urged us to decide the Festo issue on the record now before us. We of course are not bound by the wishes of the parties on a question such as this. However, because resolution of the issue turns on whether Insituform's rationale underlying the narrowing amendment bore no more than a tangential relation to accused Process 1, and because the record has been fully developed on this point, we agree that we can decide the issue. See Festo III, 344 F.3d at 1370 ("[W]hether the patentee has established a merely tangential reason for a narrowing amendment is for the court to determine from the prosecution history record without the introduction of additional evidence, except, when necessary, testimony from those skilled in the art as to the interpretation of that record.").

Plaintiffs urge that nothing in either Festo II or Festo III invalidates Insituform II, where we determined that plaintiffs were not barred by prosecution history estoppel from asserting infringement under the doctrine of equivalents. Plaintiffs contend that any presumption of surrender is rebutted because the rationale underlying the amendment narrowing claim 1 to a single cup process bears at most a tangential relation to the infringing equivalent — the multiple-cup method of Process 1. Specifically, plaintiffs assert that the reason for the amendment was to overcome the prior art teaching of a single vacuum source at the far end of the tube liner. As such, plaintiffs argue, the amendment is, at most, only tangentially related to Process 1, which places multiple cups near the resin front.

For their part, defendants note that claim 1, as originally filed, covered a process using single or multiple cups at any location downstream of the resin front. See Insituform I, 99 F.3d at 1108. They also note that we construed claim 1, as amended, to cover a single vacuum cup, which inherently creates a discontinuous vacuum. Id. at 1106. Defendants thus argue that accused Process 1 falls squarely within the territory surrendered by the narrowing amendment.

For the reasons which follow, we hold that plaintiffs have rebutted the Festo presumption that a narrowing amendment made for a reason of patentability surrenders the entire territory between the original claim limitation and the amended claim limitation. See Festo II, 535 U.S. at 740-41, 122 S.Ct. 1831. We reach this conclusion because we conclude that the prosecution history establishes that "the rationale underlying" the amendment narrowing the scope of literal claim coverage from multiple cups to a single cup bears "no more than a tangential relation to the equivalent in question," accused Process 1. Id. Therefore, application of the doctrine of equivalents in this case was not barred. Accordingly, we again affirm the judgment of the district court that Process 1 infringed claim 1 of the '012 patent under the doctrine of equivalents.3

In Insituform I, we construed claim 1 of the '012 patent as limited to "a process using only one vacuum cup which inherently creates a discontinuous vacuum." Id. at 1106. Based upon that construction, we affirmed the district court's JNOV that Firstliner's Process 1, employing multiple cups beyond the resin, did not literally infringe claim 1. Id. As noted, we also held, however, that Insituform was not barred by prosecution history estoppel from asserting that Process 1 infringed claim 1 under the doctrine of equivalents. Id. at 1109. In so holding, we first looked at the original claims in Insituform's application. Of those, only the first four are relevant to this appeal. Those claims recited:

1. A method of impregnating a flexible tube comprising an inner layer of resin absorbent material and an outer layer in the form of an impermeable film, wherein the resin absorbent layer is impregnated with a curable resin by applying a vacuum to the inside of a flexible tube whilst the resin is brought into impregnation contact with the resin absorbent material, the impermeable film serving as a means to prevent ingress of air into the interior of the tube, whilst the impregnation process is taking place.

2. A method according to claim 1, wherein the resin is introduced into one end of the tube in a quantity calculated effectively to impregnate all of the resin absorbent material of the tube, and the vacuum is applied to the interior of the tube, downstream of the resin mass, so that the resin will tend to flow towards the vacuum application region.

3. A method according to claim 2, wherein the lining tube containing the mass of resin is fed through a pressure applying nip, such as may be defined by a nip roller, which, together with the movement of the tube, squeezes the resin in a direction towards the region of the application of the vacuum, at the same time flattening the tube and assisting in the even distribution of the resin.

4. A method according to claim 2, wherein the vacuum is applied through a window in the film in the wall of the tube by means of a cup applied to said window and connected to a source of vacuum by means of a flexible hose, whereby the cup can move with the tube during its movement relative to said nip, the cup being moved and applied to a position spaced downstream from the previous window, said previous window being sealed by means of a patch or the like, whereby the process is repeated for respective lengths of the tube until the entire tube length has been impregnated.

As can be seen, the position and number of vacuum cups were not specified in independent claim 1. Neither did claim 1 specify the location of the vacuum source. Dependent claim 2 referred to the vacuum being applied to the interior of the tube, "downstream of the resin mass," while dependent claim 3 stated that the resin is squeezed "in a direction towards the region of the application of the vacuum." It was only in dependent claim 4 that the inventor recited application of the vacuum through a window in the wall of the tube by means of a cup applied to the window, as well as repositioning of the cup. All four claims were rejected over United States Patent No. 4,182,262 to Everson ("Everson").

We stated in Insituform I that the original four claims "were rejected over Everson, which discloses both the use of a continuous vacuum and the creation of that vacuum from only a single vacuum source at the far end of the tube opposite the resin source." Id. at 1108. The objection was overcome by amending claim 1 to include, in a different form, the limitations of original dependent claims 2-4. Further examining the prosecution history, we determined that Insituform had stated to the examiner that the problem with Everson was that Everson's method was ineffective when dealing with a long length of tube because it required an exceedingly large suction compressor. We pointed out that Insituform solved this problem by placing the suction source closer to the resin front, thus allowing the use of a smaller suction compressor. Id. Based on our examination of the prosecution history, we concluded that Insituform was not estopped from asserting that Inliner's multiple cup process infringed claim 1 of the '012 patent under the doctrine of equivalents:

[I]t cannot be said that a reasonable competitor could conclude that Insituform relinquished coverage of processes using either multiple vacuum sources or a continuous vacuum. At no point did Insituform indicate that the Everson problem could be solved only in the manner used by Insituform, i.e., Insituform never stated that the problem could not be solved by using more than one vacuum source or a continuous vacuum. Rather, the only express limitation put on the invention by Insituform was the use of a vacuum source close to the resin.

Id. at 1109. We remanded the case to the district court for further proceedings on whether Process 1 infringed claim 1 under the doctrine of equivalents.

On remand, the district court held that Process 1 infringed claim 1 under the doctrine of equivalents, and the case returned to us on appeal in Insituform II. On appeal, Firstliner argued that Warner-Jenkinson Co. v. Hilton Davis Chemical Co., 520 U.S. 17, 117 S.Ct. 1040, 137 L.Ed.2d 146 (1997), issued after Insituform I, limited the doctrine of equivalents so that it could not apply in the case. Firstliner pointed to Warner-Jenkinson's holding that where no explanation is given for an amendment made during prosecution of a patent, a presumption is to be applied against the patentee that the amendment was made for purposes of patentability. Firstliner asserted that when Insituform amended claim 1 in response to the examiner's 35 U.S.C. § 103 rejection over Everson, it necessarily gave up coverage of any process in which the vacuum was created at multiple vacuum sources because it provided no explanation for that narrowing amendment. Insituform II, 161 F.3d at 691. We rejected this argument, pointing out that, during prosecution, Insituform had explained the reason for the amendment of claim 1:

The stated reason ... for Insituform's amendment to overcome the Everson reference was to avoid the need to use a large compressor when the vacuum is created a significant distance from the resin source. The Warner-Jenkinson presumption, therefore, which comes into play only when no explanation is given for a claim amendment, is not applicable to this case because Insituform made clear that the reason for the amendment was to overcome the prior art teaching creation of a single source vacuum at the far end of the liner.

Id. at 692 (citation omitted, emphasis in original). Having rejected Inliner's prosecution history estoppel argument, we went on to affirm the district court's judgment of infringement under the doctrine of equivalents. Id. at 692-93. As noted above, however, we subsequently reversed the judgment of infringement in Insituform III based on our short-lived complete bar rule arising out of Festo I.

In our view, Insituform has rebutted the Festo presumption. The prosecution history and our discussion of that history in Insituform I and II compel the conclusion that the amendment limiting the literal scope of claim 1 to a single cup process bears "only a tangential relation," if that, "to the equivalent in ques